Preconditioning of human skeletal myoblast with stromal cell-derived factor-1α promotes cytoprotective effects against oxidative and anoxic stress

Background and Objectives: The incidence of human autologous transplanted skeletal myoblast (SkM) cell death in ischemic myocardium was higher in the first few days after cell therapy. We proposed that human SkM treated by human stromal cell-derived factor (SDF-1α) protein or tranfected by SDF-1α, precondition them against oxidative or anoxic injury. Methods and Results: The purification of human SkM (80~90%) culture was assessed for desmin and CXCR4 expression using immunostaining and flow cytometry respectively. Cells were transfected to overexpress SDF-1α or treated with rSDF-1α (10~200 ng/ml, 1~4 h) were either exposed to anoxia or treated with 100μM H₂O₂ for different time periods (1~6 h anoxia) (1~3 h H₂O₂). Optimized conditions for transfection of SDF-1α gene into human SkM were achieved, using FuGene^TM6/phSDF-1α (3:2 v/w, 4 h transfection) with 125μM ZnCl2 (p<0.001), up to 7 days post-transfection as compared with transfected SkM without ZnCl₂ and non-transfected control cells. Transfection efficiency was assessed by immunostaining, ELISA, western blots and PCR. LDH analysis showed significant decrease in release of LDH after exposure to 6 h anoxia or 100μM H₂O₂ for 2 h as compared with the normal un-treated or un-transfected SkM (p<0.001). In western blots assay, SDF-1α over-expressing human SkM or treated with rSDF-1 α induced marked expression of total Akt (1.2-fold) and phospho-Akt (2.7-fold), Bcl2 (1.6-fold) and VEGF (5.8-fold) after exposure to 6 h anoxia as compared with human SkM controls. Conclusions: The preconditioning of donor transplanted human SkM with SDF-1α increased cell survival and promoted cytoprotective effect against oxidative or anoxic injury that may be an innovative approach for clinical application.